Ezra Klein now has a blog at the Washington Post and one of his first posts concerns the new focus on menu labeling among some in the public health field. He writes,

Sen.Tom Harkin (D-Iowa) and Rep. Rosa DeLauro(D-Conn.) are reintroducing the aptly-named MEAL Act. "MEAL" stands -- somewhat awkwardly -- for Menu Education And Labeling. That is to say, it stands for calorie counts. Right there on the menu. Next to your food. So you know. Harkin and DeLauro want to see restaurants with more than 20 locations displaying the total calories, sodium, saturated and trans fats, and carbohydrates of each dish right next to its name on the menu. Or, as the case may be, the menu board. . . .

The theory here is simple. Ignorance, as my Libertarian friends claim, might be bliss. But it also makes you fat. It's not simply that consumers don't know how many calories are in restaurant meals. It's that repeated studies show they systematically underestimate how many calories are in restaurant meals. . . . Studies show that even nutritionists tend to lowball their estimates at fast food restaurants, coming in 200 to 600 calories below the mark. . . .

Hence: Menu labeling. The key insight here is that small changes in behavior can have large impacts on outcomes. A Health Impact Assessment (pdf) prepared for the city of Los Angeles estimated that if calorie labeling convinced a mere 10 percent of large-chain patrons to order meals that were merely 100 calories lighter, then menu labeling "would avert 38.9% of the 6.75 million pound average annual weight gain in the county population aged 5 years and older." Get 20 percent to reduce their meals by 75 calories? You've knocked out 58.3 percent of the projected 6.75 million pounds. That's huge. . . .